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Recent scientific advances mean that we now have a better understanding of the underlying factors that can increase someone’s risk of HIV infection. At the same time, we also have more effective interventions to prevent HIV transmission. Despite these advances, HIV transmissions in Canada are continuing at a high rate and certain populations remain disproportionately affected by the HIV epidemic. But even within these populations, we know that HIV risk is not evenly distributed. A complex range of interrelated and synergistic factors contribute to a higher vulnerability to HIV infection for some individuals. A more holistic and comprehensive approach to HIV is needed, but a major barrier to such an approach is the fragmentation of the diverse range of services needed to address HIV risk for individuals within these populations.

This article reviews our new understandings about HIV risk and prevention and explores how HIV prevention can be improved.

HIV in Canada

According to estimates from the Public Health Agency of Canada (PHAC), there were 2,570 new HIV infections in Canada in 2014.1 The latest estimates also show that certain populations continue to be disproportionately affected by the HIV epidemic. These populations include gay men and other men who have sex with men (MSM), Aboriginal people, people who use injection drugs, and people from HIV-endemic countries. Additional research tells us that transgender people in Canada may also be disproportionality affected by HIV.2 According to the latest PHAC estimates, the rate of HIV infection among people from HIV-endemic countries is 6.3 times higher than the rate for other Canadians, and the rate among Aboriginal people is 2.7 times higher than the rate for non-Aboriginal Canadians.1 Estimates from 2011 indicate that MSM are 71 times more likely to get HIV than other men and people who use injection drugs are 46 times more likely to get HIV than people who do not.3

But these numbers don’t tell us the whole picture. HIV risk is not evenly distributed within these populations. Research tells us that many psychosocial factors occur unevenly across individuals within these groups and can combine synergistically to increase HIV risk. For example, in a study of gay, bisexual and other MSM in the U.S. it was found that the co-occurrence of four to five psychosocial factors (depression, alcohol use, stimulant use, polydrug use and childhood sexual abuse) created an 8.6-fold higher risk for HIV infection among men who experienced these factors over a four-year period compared to those who did not experience any of these factors.4 MSM with fewer psychosocial factors were also at higher HIV risk, but to a lesser extent. Canadian data also support that psychosocial factors syndemically impact vulnerability,5,6 and that similar factors interact synergistically to increase HIV vulnerability in other populations, such as Aboriginal peoples.7

Underlying reasons for increased HIV risk

Factors that increase HIV vulnerability are diverse and complex. And, while these factors are inter-related and difficult to completely disentangle from each other, they are often distilled down into different categories, such as the biological, behavioural and psychosocial-structural.

At the most basic level, HIV transmission occurs from an exposure to HIV. However, not all exposures carry the same risk of HIV transmission and a range of biological factors can increase the HIV risk from an exposure. These factors include certain routes of exposure (for example, on average, receptive anal sex carries the highest risk of HIV transmission for the HIV-negative partner); the presence of a sexually transmitted infection (such as gonorrhea or syphilis); the absence of post-exposure prophylaxis (PEP) or pre-exposure prophylaxis (PrEP) in the HIV-negative partner; and a higher viral load in the fluids of the HIV-positive partner.

In addition, there are a range of behavioural factors that can increase the chance that an exposure occurs in the first place (for example, a higher number of sexual or needle-sharing partners or lack of consistent condom use) or the chance that the exposure leads to HIV infection (such as lack of adherence to PEP or PrEP).

The psychosocial-structural factors that can increase HIV vulnerability include social determinants of health (SDOH) inequities and syndemic health issues. SDOH inequities include poverty, underemployment, illiteracy, underhousing, incarceration, and inadequate coping skills and social support networks. Many of these inequities are related to broader issues such as stigma, homophobia, racism and colonization, and poor access to education and health-related services. Syndemics refer to various co-occurring issues that can combine synergistically to increase HIV risk.8 These include substance use and addiction; anxiety, depression, and other mental health issues; and trauma, violence and abuse, including childhood abuse, sexual abuse, and intimate partner violence. Research shows that the more syndemic issues a person faces, the greater their risk for HIV infection.4,5,8,9

These three different types of factors that can increase HIV vulnerability (biological, behavioural, and psychosocial-structural) are strongly related.9 Inequities in the SDOH can exacerbate syndemic health issues, and SDOH inequities and syndemic issues can increase the prevalence of biological and behavioural HIV risk factors. For example, SDOH inequities and syndemic health issues can make it difficult for an individual to use, access, and adhere to an HIV prevention strategy. They can also make it difficult for people living with HIV to access HIV testing, care and support, and treatment services – potentially resulting in a higher overall viral load in certain populations (also known as community viral load).10 A higher community viral load can increase the average risk from an exposure to HIV for people within that population or group. Higher rates of HIV infection within these populations can also create a higher prevalence of HIV (that is, more individuals with HIV in the community), increasing the chance that an exposure to HIV will occur (particularly within small sexual and injecting networks), thus further increasing HIV transmission risk. This may partially explain why some populations have a higher rate of HIV infection, but do not engage in a higher rate of behaviours that can lead to HIV infection.11,12,13  These examples highlight the overlap both within and between these three different types of factors that can increase HIV risk and that vulnerability to HIV goes beyond individual behaviours and choices.

The need for combination HIV prevention

Our improved understanding of the underlying factors contributing to greater HIV vulnerability – in addition to the expanding evidence base for HIV prevention and the emergence of new tools – has broadened the range and depth of services and interventions which can now be considered relevant to HIV prevention. Some of these services are directly related to HIV (HIV risk-reduction counselling and PrEP, for example), while others may seem more distantly related (such as mental health and addiction services). Some interventions can be considered biomedical (such as PrEP and condoms), while others are behavioural (such as social marketing campaigns to improve condom use, medication-adherence counselling, and mental health counselling) or psychosocial-structural (such as improved access to PrEP, mental health services or supervised injection services). Some services can only be provided by physicians (PrEP, anti-depressants and methadone, for example), while others can be provided by a broader range of care providers (HIV risk-reduction and mental health counselling, for example).

The terms combination HIV prevention, comprehensive prevention and holistic prevention are not new, and are based on the idea that there is overlap and synergy between these different interventions and services.14 For example, the success of biomedical tools relies on behavioural and psychosocial-structural interventions to address an individual’s needs in a holistic way and subsequently facilitate uptake, access, and consistent and correct use.

A significant barrier toward the adoption of a more comprehensive approach to HIV prevention is the fragmentation and siloization of the different services relevant to HIV prevention. Often, the diverse array of HIV-related services is not well integrated or connected and, as a consequence, there are missed opportunities to effectively address an individual’s risk of HIV infection in a holistic way. For example, non-clinical and clinical services are often poorly linked, as are services that are directly and distantly related to HIV.

A research-based example that highlights the importance of a comprehensive approach – and the potential negative impact of service fragmentation – comes from PROJECT Explore, the largest ever behavioural HIV prevention intervention study among gay men in the United States.15 The PROJECT Explore intervention involved several one-on-one HIV risk-reduction counselling sessions, which were found to reduce the overall rate of HIV infection among men in the study by 18%. This risk reduction was small, and additional analyses suggested that the intervention had no effect for men with a history of childhood sexual abuse.16 Of concern, 40% of men in this study reported a history of childhood sexual abuse, and these men were also more likely to have depression and use street drugs and alcohol. The high overall prevalence of these health issues may explain the small overall reduction in HIV risk provided by the HIV risk-reduction counselling.

The PROJECT Explore example highlights the importance of better integrating services and using interactions with clients to screen them for syndemic health issues and SDOH inequities and, if appropriate, engaging them in additional services to address them. Once clients are engaged, strategies are needed to link and retain them across a continuum of relevant services, and ensure such interactions do not become missed opportunities to improve holistic health and reduce HIV vulnerability. There is also a need to ensure the needed services are available, are appropriate for the population being served, and are resilience-based.

Time for an HIV prevention cascade for people at ongoing risk for HIV infection?

In recent years, the fragmentation of services relevant to the health and well-being of people living with HIV has received a significant amount of renewed attention. This can be seen in the recent focus on the HIV care cascade, which is a way of visualizing the engagement of people living with HIV in the services necessary to improve their health and reduce their risk of HIV transmission.17 These services include those to improve HIV testing, linkage to care, retention in care, HIV treatment initiation, and treatment adherence. The focus on this cascade has led to the development and evaluation of interventions to improve linkage across these services.18

The disconnect between services aimed at improving health and reducing HIV risk for people at high ongoing risk of HIV infection is in need of similar renewed attention. Some organizations and agencies have begun to include a prevention component in their HIV care cascades, but little work has been devoted to the monitoring and evaluating of engagement in this cascade.

What can be done?

There are several actions that can be taken to improve engagement and linkage of people at high risk of HIV infection in the range of services necessary to improve their health and reduce their risk of HIV infection.

Not all organizations have the funding, mandate or infrastructure to integrate additional services into the work they are already doing. One way to improve linkage between services is to undertake a service mapping activity to understand what range of clinical and non-clinical services are available in your area and where they are located.

Developing formal and informal new partnerships and relationships with other local organizations that offer complementary services may be an effective way to facilitate linkage to additional services.

Interventions to improve engagement and linkage

Simply knowing if and where services are available – and where the gaps exist – is not enough. Interventions may be needed to actively connect clients to the services, and ensure they are linked and retained in these services. In closing, we highlight two examples of how interventions are being used to improve engagement and linkage  within the Canadian context.

Health Promotion Case Manager Program, Vancouver, BC

Understanding that people at ongoing high risk for HIV infection need additional supports to prevent HIV, Vancouver Coastal Health funds a number of health promotion case managers. The case managers are hosted by community-based organizations in Vancouver and work with populations disproportionately impacted by HIV, including gay, bi and other MSM, men in serodiscordant couples, women, trans people, youth, Aboriginal people, immigrants and refugees. These programs are designed to build client self-efficacy to prevent HIV.

The Health Promotion Case Manager Program uses a comprehensive approach to health which acknowledges that HIV prevention must address both individual and structural factors that contribute to ongoing HIV vulnerability. Case managers work with clients to decrease vulnerability to HIV risk by focusing on the client’s strengths and resiliency. Case managers support clients to identify their health and wellness goals, including changes in behaviour, lifestyle, relationships, mental health and substance use and then help clients achieve their goals. Additionally, structural barriers that impact a client’s health are addressed by providing support to apply for social assistance, find housing, access community support services, and support to resolve any immigration or legal issues.

Clients work with case managers over a period of one to five months; clients determine the level and duration of support they need. Once a client feels they no longer need the support of a case manager, case managers will work with the client to transition clients to other community supports and services and follow up with clients for three to six months after the transition has been made.

Making the Links, Toronto, ON

Making the Links offers free and confidential short-term counselling and community referral services for gay, bisexual and other MSM who have difficulties engaging in safer sex practices. The program recognizes that decision-making can be impacted by factors that go beyond the mere availability of condoms or knowledge of the risks for HIV and STIs such as relationship difficulties, partner abuse, mood changes, substance misuse, lack of comfort with negotiation, loneliness, or experiences of racism.

A counsellor helps guys explore how these factors impact their ability to engage in safer sex practices, identify their strengths and give them the tools to develop healthy coping mechanisms that positively impact their ability to reduce the risk of acquiring HIV.



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About the author(s)

James Wilton has a Master's Degree of Public Health in Epidemiology from the University of Toronto and previously worked as CATIE's Biomedical Science of HIV Prevention Coordinator for six years. He is currently involved in several research projects related to HIV pre-exposure prophylaxis and HIV risk communication.

Logan Broeckaert holds a Master’s degree in History and is currently a researcher/writer at CATIE. Before joining CATIE, Logan worked on provincial and national research and knowledge exchange projects for the Canadian AIDS Society and the Ontario Public Health Association.